Electric communicating system



May 26, 192& 1,539,421

v C. KRAFT ELECTRIC COMMUNICATING SYSTEM Filed July 6, 1920 STATXON l IIIIIIIIILL HIGH RESISTAFfCE Low Rzsxsmwca STATION MrA JES: WW gqfyk $1.3m

ATTORNEY Patented May 26, 1925.

ITED "STATES PATENT "oFFic E.

CARL KRAFT; or NEW yonx u. Y; ASSIGNQR orv ONE-HALF To nnsrnwnm GATTE'R, QOFNEW YORK, 1v. Y.

v TELJIC'TIRIC COMMUNICATING SYSTEM.

Application filed July 6,

disymtcher or starter controlling a certain f groupot elevators or vice verso.

' There is alson grmviu-g demand tonthe so ca'lcd operator-less elevators perticularly in warhouses, marine terminals and garages "where a group. of elevators niay all be operated by one person at a central point ren'iotely situated from the elevators and where it is necessary for. the central. controlor dispatcher toogivetorders tothe Vtl'l'lOl-SallOtQPS such as to close the. elevator doors Sothat the car may besubject tothe dispatohcrs control. Theperfection of theloud speakingtelephone of both receiving and transmittingtypediasfpointed the way :to expedite. and insure safety in theoperati on ofthese and iother type of elevatorinstallationswhere, as providedby my inven tion; the cost 0finstall-ing such' a system is reduced to aminimum enddoes not offset the manitold advantages in speed and safety I obtained.

Anobject ofmy invention-ism provide safety, in the case of fire orotherwise, by means of a system of loud speaking telephonic communication in connection .with

elevators so that the operator in the :car need not 'lQtIVGdHSCtIl' switch andqeopardize .oontrolof' the car in order to listen ior spezik to the dispatcher .or. :thatany person outside a banker-group ot' elevatorsznt auy floor may communicate iii-1th i the :atlISPiLtQllQl from a point remote from the elevators. I

Afurther ol iiect of any invention isto provide an electrioalcironit consistingof only two wires from outlying stations to a central station for the purpose of; communication thru :loiid speaking transmitters and receivers in' each outlying station and :sig-

nalling froni said' outlying stations in a selective manner so that the-cost ojt wiring may be reducedto a minimum and not,

vduced to 7 wires.

A further object of my invention is to provide that in such a two wire communicating system for elevators where any gri'iunded connections would necessarily go thru thesteel rails or hoist ropes -.i1nd hence be subject to great variations in resistance such grounded circuit heuot usednsa talkjug circuit.

A. further object oi my iuve1 1tiou is to provide that in such a system of communication the operator in the car or person at a landingniay signal the dispatcher 'hru a selective means such as electric lamps or an-nmiciators and that u seli hoiding e1ectin-magnetic device be providodtwith ouch such light or anuunciator so that once clos- Jug said circuitwill establ sh it and hold it although the manual operation of establishing it may be but momentary, 7

Another object of my invention is to provide-such a system with the loud speaking .receiver and transmitter at theoutlyingstm tlons so connected in a two wire circuit thut the receiver does not receive or amplify the sounds impressed upon the transmitter and hence does not permit of the ob eot on- -able amplification of the voice of any one using that transmitter.

lieference to the accompanying drawings will aid in explanation of my invention. The I figure shows a preferredembodiment of the circuits, connections and units used With my invention but it must be understood that numerous other circuits and coinbinations would be within the-scope of my claims.

Referring to the drawing in detail the keys h n -and R are, located at the outlying stations, three of which are shown as No. 1, 2 and 3, which, in this case would he elevator cabs. One side of these keys is grounded at G G and G Loud speaking, high resistance transn iitters T T T containing in circuit :variable resistances O O and 0; respectively are connected in parallel with loud speakii'iglo'w resistance receivers R B and R all connected as shown with two wires leading thru the traveling cables TC T and T0 At the central or dispatching station is the ordinary transmitter X and receiver Y of low resistance together with the hook "for same H containing contacts A, P and U; the battery 1%, the buzzer Z connected to ground G the lights L L and L the selfholding coils M M M with their contacts C C and C connected to grounds G G and G and switch keys S S and S of se lective switches all for their respective outlying stations 1, 2 and 3.

Switches 8,, S and S, are identical in construction and may be understood by an explanation of any one such as S containing contacts E, F and I, J, bridge N being insulated from arm D.

The operation of the circuit might be as follows: The operator at the outlying station or in the car 3 would momentarily press key K which would establish the circuit from G, thru K thru one wire of the trayeling cable, thru coil M thru light L contact E of switch S normally open on in the made position, thru D to the common wire of the selector switches to battery B, to contacts and bridge P, U, normally closed by receiver X hanging on hook H and then thru buzzer Z again to ground. Coil M being momentarily energized would close contact C normally open and establish circuit from ground G to G, as before and cause buzzer Z to operate although K has meanwhile opened.

The central starter or dispatcher now removes receiver' Y and presses selector switch S either or both operations opening buzzer and light ground circuits by opening contacts P, U, and E, deenergizing M and hence opening C The talking circuit is now made and all grounds of the selective signal circuit removed. The dispatcher at master phone speaks into the low resistance transmitter X which is carried thru contact A, now established, receiver Y, contacts I, J of selector switch S one traveling cable wire, across low resistance receiver R which is not short circuited by high resistance transmitter T then back thru the other traveling cable wire to contacts E, F of selector switch S thru the common wire of selector switches, thru battery B again to transmitter X.

The outlying station responds without any further movement directly thru loud speaking high resistance transmitter T variable resistance 0 having been adjusted for the line distances in each case, over the same circuit to receiver Y, no eli'ect caused by T is apparent in R since no battery is connected in circuit.

The dispatcher can of course speak at any time directly to outlying station or operator in car without necessity of any operation on the part of the latter.

hat I claim and what I desire to secure by United States Letters Patent is 1. In an electric communicating system the combination, in a two wire circuit from each of a plurality of elevator cars to a central dispatcher station, of a loud speaking receiver of low resistance with a loud speaking transmitter of high resistance at each car connected in parallel with said low resistance receiver so that the transmitter is not a short circuit for the receiver and so that the receiver does not receive the effects of the transmitter; batteries common to all and connected in series with one of said wires to each car; a master telephone at said dispatcher station with low resistance transmitter and receiver; the hook of said master telephone; which said hookwhen in talking position makes contact connecting the common batteries in series with the master telephone transmitter and receiver and to the other wire of said wires to each car as selected at the dispatcher station; selector switches arranged to open both wires to the car and by means of which said selection can be made.

2. In an electric communicating system the combination, in a two wire circuit from each of a plurality of devator cars to a central dispatcher station, of a loud speaking receiver of low resistance with a loud speaking transmitter of high resistance at each car connected in parallel with said low resistance receiver so that the transmitter is not a short circuit for the receiver and so that the receiver does not receive the effects of the transmitter; batteries common to all and connected in series with one of said wires to each car; a master telephone at said dispatcher station with low resistance transmitter and receiver, the hook of said master telephone; which hook when in talking position makes contact connecting the common batteries in series with the master telephone transmitter and receiver and to the other wire of said wires to each car as selected at the dispatcher station; selector switches arranged to open both wires to the car and by means of which said selection can be made; each elevator cab containing a call switch mounted convenient to the operator the circuit to one side of which is grounded in the cab and the other side connected to one of said wires; a visual indicating device in series with said call switch; a contact on the respective selector switch also in series with said call switch and with said visual indicating device, which contact is made when the selector switch is in a non-talking position and thence in series to the battery;

a bridge contact on but insulated from the hook of the master phone in series therewith which bridge contact is made when said telephone is in a talking position; an auditory indicating device in series therewith and then to a ground connection so that when the call switch in any particular car is closed the auditory indicating device will operate and the proper visual indicating device will signal the dispatcher and when said hook or selector switch is in talking position the ground circuits are entirely opened.

3. In an electric communicating system the con'ibination, in a two wirecircuit from each of a plurality of elevator cars to a central dispatcher station, of a loud speaking receiver of low resistance with a loud speaking transmitter of high resistance at each ear connected in parallel with said low resistance receiver so that the transmitter is not a short circuit for the receiver and so that the receiver does not receive the eiiects of the transmitter; batteries common to all and connected in series witlrone of said wires to each car; a master telephone atsaid dispatcher station with low resistance translnitter and receiver; the hook of said master telephone; which hook when in talking position making contact connecting the common batteries in series with the master telephone transmitter and receiver and to the other wire of said wires to each car as selected at the dispatcher station; selector switches ar ranged to open both wires to the car and by means of which said selection can be made; each elevator cab containing a call switch mounted convenient to the operator,

the circuit to one side of which is grounded in the cab and the other side connected to one of said wires; a small solenoid switch with coil in series with said wire and to one side of the contact for said solenoid switch, the other side of the contact being grounded, the other side of said coil being connected in series with a visual indicating device; a contact on the respective selector switch also in series therewith which contact is made when the selector switch is in a non-talking position and thence in series to the battery; a bridge contact on but insulated from the hook of the master telephone in series there with, which bridge contact is made when said telephone is in a talking position; an auditory indicating device in series there with and then to a ground connection so that when the call switchin any car is momentarily closed the solenoid switch contact closes and causes the coil thereof to be maintained thru the grounded connection established by said contact and maintained until the hook or selector switch takes the talking position and entirely removes all grounded circuits;

In testimony whereof I have signed my name to this specification this 3rd day of May, 1920.

CARL KRAFT. lVitnesses MARIE Connor, A. L. J oYoE; 

